Not Applicable.
(1) Field of the Invention
This invention relates to an apparatus for converting an input AC signal to an alternatively configured output signal and providing the output signal to one or more devices. More specifically, the present invention relates to a method of producing a modulated AC signal for use by electrical devices as well as an outlet unit through which the AC signal may be channeled.
(2) Description of the Related Art
There exist outlet units for mating with the prongs of a plug through which power is to be supplied to a device which employ mechanical switches to detect the insertion of a plug. An example of an existing outlet unit is described in U.S. Pat. No. 6,016,016 of Starke et al. the disclosure of which is incorporated herein in its entirety by reference. Some existing outlet units make use of a plug case sensor to determine when it is safe to supply power to a plug. A plug case sensor senses the physical contact of a plug against a surface of the outlet unit. Power is enabled to a device only when the plug of the device exerts sufficient pressure against the plug case sensor to indicate that the plug is sufficiently connected to the outlet unit. Unfortunately, when used on a vehicle, the vibration which often attends the motion of the vehicle is sufficient to dislodge a plug from the plug sensor case. In such circumstances, provision of power to the plug from the outlet unit is rendered intermittent.
Many existing outlet units are attached to In Seat Power Systems (ISPS). An example of an ISPS is described in U.S. Pat. No. 5,754,445 of Jouper et al. the disclosure of which is incorporated herein in its entirety by reference.
There is therefore needed an outlet unit which can detect a plug insertion without the need for mechanical switches extraneous to the plug itself. In addition, it is preferable to utilize an outlet unit which does not rely upon a plug case sensor to determine when there is sufficient contact between the plug and the outlet unit to continue to provide power. Lastly, there is needed an ISPS configured to filter out the Electro-Magnetic Interference (EMI) produced by an offending device so that the device may continue in use without the need to restrict the provision of power to the offending device.
Accordingly, one aspect of the present invention is drawn to an outlet unit for providing a supply voltage to the prongs of a plug comprising a housing having a plurality of electrically conductive plug channels for receiving the prongs of the plug, a shutter rotatably mounted to the housing and operative in one of a first and a second position, the shutter having openings for receiving the prongs of the plug wherein only when in the second position the openings of the shutter and the plug channels are aligned permitting axial displacement of the prongs into the housing, and a strike plate located between the housing and the shutter for preventing the rotation of the shutter to the second position absent axial displacement of the prongs sufficient to engage the strike plate.
Another aspect of the present invention is drawn to An apparatus for converting a DC input signal to one or more AC output signals comprising a timer/control for emitting modulated timing and logic control signals, and a power converter for receiving the modulated timing and control signals comprising a plurality of master chopper oscillators responsive to the modulated timing and control signals so as to alter the voltage of the DC input signal for output as a single phase of one of the AC output signals, a plurality of current limiting chopper oscillators responsive to the modulated timing and control signals so as to alter the voltage of the DC input signal for output as a single phase of one of the AC output signals, a current integrator in electrical contact with one of the AC output signals the current integrator capable of measuring current drawn from the AC output signal and modifying the control signals of the current limiting chopper oscillators so as to shorten the duration of time of each positive or negative voltage phase of the AC output signal.
The above-stated objects, features and advantages will become more apparent from the specification and drawings that follow.